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Toyota Corolla Repair Manual: Circuit description

When a misfire occurs in the engine, hydrocarbons (hc) enter the exhaust in high concentrations. If this hc concentration is high enough, there could be an increase in exhaust emissions levels. High concentrations of hc passing through the catalyst also cause to temperature of the catalyst to increase, possibly damaging the catalyst. To prevent this increase in the emissions and limit the possibility of thermal damage, the ecm monitors the misfire rate. When the temperature of the catalyst reaches a point of thermal degradation, the ecm will blink the mil. For monitoring misfire, the ecm uses both the camshaft position sensor and crankshaft position sensor. The camshaft position sensor is used to identify misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. The misfire counter increments when crankshaft rotation speed variations exceed threshold values.

The ecm illuminates the mil if the misfiring rate exceeds a threshold value and could cause emissions deterioration.

Hint:

Hint

: when codes for a misfiring cylinder are recorded repeatedly but no random misfire code is recorded, it indicates that the misfires have been detected and recorded at different times.

Reference: inspection using oscilloscope with the engine idling, check the waveform between terminals #10 to #40 and e01 of the ecm connectors.

Hint

: the correct waveform is as shown.

Monitor description

Monitor description

The ecm illuminates the mil if the misfiring rate exceeds a threshold value

The ecm illuminates the mil if the misfiring rate exceeds a threshold value and could cause emissions deterioration.

The ecm will illuminate the mil when the percent misfire exceeds the specified limit per 1,000 engine revolutions.

One occurrence of excessive misfire during engine start will set the mil. Four occurrences are required to set the mil 1,000 revolutions after engine start. (2 Trip detection logic) the mil blinks when percent misfire causing catalyst damage per 200 revolution met 3 times (1 time if the engine rpm is in high speed range). (Mil blinks immediately)

Monitor strategy

Typical enabling conditions

Typical enabling conditions

Typical malfunction thresholds

Typical malfunction thresholds

Wiring diagram

Wiring diagram

Refer to dtc p0351  for the wiring diagram of the ignition system.

Confirmation driving pattern

Random/multiple cylinder misfire detected
Dtc p0300 random/multiple cylinder misfire detected Dtc p0301 cylinder 1 misfire detected Dtc p0302 cylinder 2 misfire detected Dtc p0303 cylinder 3 misfire detected Dtc p0304 cylinder 4 misfire ...

Confirmation driving pattern
Connect the handheld tester or the obd ii scan tool to the dlc3.  record dtcs and the freeze frame data.  set the check mode using the handheld tester .  read the value on th ...

Other materials:

Overhaul
1. Inspect 4th gear thrust clearance Using a feeler gauge, measure the 4th gear thrust clearance. 4Th gear thrust clearance: 2. Inspect 3rd gear thrust clearance Using a dial indicator, measure the 3rd gear thrust clearance. 3Rd gear thrust clearance: 3. Inspect 4th gear ...

Circuit description
The seat belt buckle switch (lh) circuit consists of the airbag sensor assy center and front seat inner belt assy (lh). Dtc b0126/b0127/27 is recorded when a malfunction is detected in the seat belt buckle switch (lh) circuit. Wiring diagram ...

Emergency flashers
The emergency flashers are used to warn other drivers when the vehicle has to be stopped in the road due to a breakdown, etc. Press the switch. All the turn signal lights will flash. To turn them off, press the switch once again. ■Emergency flashers If the emergency flashers are used ...

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